Getter cartridge



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R. H. VARIAN June 1,- 1937.`

GETTER CARTRIDGE Filed March 13,

Patented' June 1, 1937 UNITED STATES Beam mum PATENT OFFICE lGuerrini CARTRIDGE poration of California Application March` 13, 1935, Serial No. 10,882

2 Claims.

My invention relates to a getter cartridge adapted to be used in conjunction with the evacuation of an envelope, and more particularly to a cartridge in which getter material may be deposited upon a surface of relatively large dimensions within the envelope.

Among the objects of my invention are: to provide a getter cartridge which will deposit active material on an extended surface; to provide a getter cartridge adapted to deposit active material on the surface of a iinely divided material; to provide a getter cartridge which will conne the deposited active material to the surface of a nely divided substance permeable to the residual gas in the envelope to be exhausted; to provide a getter cartridge which is active without substantial deposition of active material upon the walls of an envelope to be exhausted; to provide a simple and easily assembled getter cartridge and method of use; and to provide an increased getter surface.

Other objects of my invention will be apparent or will be specically pointed out in the description forming a part of this specification, but I do not limit myself to the embodiment of the invention herein described, as various forms may be adopted 'within the scope of the claims.

Referring to the drawing:

Figure 1 is a longitudinal sectional view showing the getter cartridge of my invention in elevation, mounted within an envelope.

Figure 2 is an enlarged sectional view of a preferred form of cartridge of my invention, as mounted within an envelope.

It is quite customary in the evacuation of envelopes, particularly those envelopes containing electrodes adapted to cooperate to produce an electrical discharge therein, to vaporize a getter material as the last step in evacuation, in order that a film of condensed getter material on the walls of the tube may be able to gather up and hold a number of the remaining gas molecules. Getter materials are numerous, magnesium, calcium and aluminum are examples. They are usually vaporized by the application of heat, applied either directly to the materials themselves or, as is more common, to a getter container or cup in which the getter ma,- terial has been previously deposited. The vapor created when the material is heated is usually allowed to condense upon the inner walls of the envelope in a ne lm. The material thus deposited remains active throughout the life of the tube to gather and occlude gas molecules.

In many electrical discharge devices, however,

(Cl. 25o-27.5)

stem is joined to the main body of the envelope.

In mercury tubes designed to operate with an amount of mercury free Within the tube in liquid phase, any amount of getter lm is bad, as the mercury Will amalgamate with many of the materials used.

Again, un-

I have found that a tube may be gettered by the use of a cartridge which will eliminate iilms or deposits on the Walls of the envelope, and yet which will furnish a suicient surface of condensed active material to give proper gettering action. Broadly, my invention comprises a' means for heating getter material, and means for causing the vapor thereby formed to pass through and be deposited upon a finely divided substance. This nely divided material is preferably permeable and open to the residual gaswithin the envelope.

My invention may be more fully understood by reference to the drawing which illustrates a preferred' embodiment of my invention. An.v E

envelope l is provided with a stem 2, such as is commonly used in the manufacture of thermionic tubes. The inner end of the stem is closed by a pinch 3, and as I have chosen as an illustration, a hot cathode rectier, a coiled filament 4 is supported by cathode leads 5 passing through the pinch. An anode 6 is supported above the cathode by an anode lead 1 sealed through the opposite end of the envelope.

A getter cartridge 8 comprises a getter cup 9 and a retaining cup I0. These cups are preferably of the same size and shape. The getter cup is provided with a quantity of the desired getter material I I, the retainer cup being formed with a series of end apertures I2. The two cups are separated by an insulating tube I3, preferinsulating, material I5. This material may be glass wool, relatively coarse glass powder, or similar divided material having interstices between the particles so that a large surface is exposed. The retainer cup I is then placed over the end of the tube to maintain the finely divided material in position. The two cups are then held on the tube by a connecting rod I6, welded to the side of the retainer cup I0, and extending to and fastened to the support lead I4. The projecting end of the support lead I4 may then be Welded to any convenient support, in this case one of the cathode leads 5.

In use, the cartridges are assembled as described, and as the tube is put together a supporting lead I4 is fastened to position the cartridge in the proper place. In this case the openings into the interior of the envelope are directed toward the stem seal. The tube is then placed on the pumps and evacuated as far as possible, and the getter cup, together with the retainer cup, heated to remove occluded gases, preferably below the vaporizing point of the getter. As thermiomc tubes of this sort are usually thoroughly baked out in an oven, the insulating tube and its contained finely divided material are freed from gas during the baking step. As the vaporization of the getter is usually the final step in exhaust, at that time heat sufficient to vaporize the getter is applied, preferably by means of an eddy currentdevice, and the getter evaporated. As the vapor passes through the finely divided material it is deposited on the extended surface of the material, and if the procedure is not carried too far the getter is condensed on the finely divided material without having any substantial amount pass out through the openings I2 into the tube. The amount of active material, however, deposited on the nely divided material is more than sufficient to give good getter action, as the residual gas within the envelope may enter the getter cartridge through the openings I2 and be held by the deposit.

It is, of course, obvious that such cartridges may be made in many sizes, and that both the path and the cross section of the finely divided material may be changed to meet various conditions. Another method which I have used successfully is to enclose a metallic getter container completely within a porous ceramic capsule, the getter vapor then being deposited in the pores of the ceramic on its way out into the envelope. Numerous other embodiments Will-be apparent to those skilled in the art.

I claim:

1. A getter cartridge adapted to be sealed within an evacuated envelope comprising a container having a metallic portion and a. nonmetallic portion, getter material in said metallic portion, and a nely divided material permeable to gas within the nonmetallic portion.

2. A getter cartridge adapted to be sealed within an evacuated envelope comprising a container having a metallic portion and a non-metallic portion, getter material in said metallic portion, a finely divided material permeable to gas within the non-metallic portion and a restricted outlet between said non-metallic portion and tlat-esaict envelope."

RUSSELL H. VARIAN. 

